From: Dave Hansen <dave.han...@linux.intel.com>
When we allocate a bounds table, we call mmap(), then add a
"valid" bit to the value before storing it in to the bounds
directory.
If we fail along the way, we go and mask that valid bit
_back_ out. That seems a little silly, and this makes it
much more clear when we have a plain address versus an
actual table _entry_.
Signed-off-by: Dave Hansen <dave.han...@linux.intel.com>
---
b/arch/x86/mm/mpx.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)
diff -puN arch/x86/mm/mpx.c~mpx-remove-unnecessary-masking arch/x86/mm/mpx.c
--- a/arch/x86/mm/mpx.c~mpx-remove-unnecessary-masking 2015-03-26
11:27:33.173486813 -0700
+++ b/arch/x86/mm/mpx.c 2015-03-26 11:27:33.176486948 -0700
@@ -431,6 +431,7 @@ static int allocate_bt(long __user *bd_e
unsigned long expected_old_val = 0;
unsigned long actual_old_val = 0;
unsigned long bt_addr;
+ unsigned long bd_new_entry;
int ret = 0;
/*
@@ -443,7 +444,7 @@ static int allocate_bt(long __user *bd_e
/*
* Set the valid flag (kinda like _PAGE_PRESENT in a pte)
*/
- bt_addr = bt_addr | MPX_BD_ENTRY_VALID_FLAG;
+ bd_new_entry = bt_addr | MPX_BD_ENTRY_VALID_FLAG;
/*
* Go poke the address of the new bounds table in to the
@@ -457,7 +458,7 @@ static int allocate_bt(long __user *bd_e
* of the MPX code that have to pagefault_disable().
*/
ret = user_atomic_cmpxchg_inatomic(&actual_old_val, bd_entry,
- expected_old_val, bt_addr);
+ expected_old_val, bd_new_entry);
if (ret)
goto out_unmap;
@@ -488,7 +489,7 @@ static int allocate_bt(long __user *bd_e
trace_mpx_new_bounds_table(bt_addr);
return 0;
out_unmap:
- vm_munmap(bt_addr & MPX_BT_ADDR_MASK, MPX_BT_SIZE_BYTES);
+ vm_munmap(bt_addr, MPX_BT_SIZE_BYTES);
return ret;
}
_
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